Grundfos Alpha 15-55 Pumps don't restart after long shutdown

ChrisMcc

I wonder if anyone has any insights into this issue - I've seen lots of reports of this on the general Internet, but no real explanation.

I have 12 Alpha 15-55FR pumps. Every summer they are shot off for about 5-6 months when the heat is off. When the heat first restarts every year, I usually get at least one that won't start up and ends up with just a "--" on the display. This year 5 of them have done this.

I am usually able to just take the motor housing off and spin the impeller to turn the motor and then reassemble and it works. Occasionally just rapping on the outside of the motor housing with a spanner will get it going. This seems like the motor isn't restarting. I've never seen any debris in the actual pump housing or impeller.

Is this a known issue with these? It happens a lot to me. I've ordered a replacement for one I couldn't get going and that now has to be the 15-58FR since the 15-55 was discontinued in August. Unfortunately these "drop in" replacements are a different size and won't drop into the bank of pumps I have so I have some replumbing ahead of me. I'd like to keep the 15-55's as long as possible to avoid this but I don't know what I can do to improve the situation.

Any thoughts?

Thanks,
Chris

hot_rod

is the impeller stuck when you remove it to "spin"? If so it sounds like a water quality issue may be sticking the impeller and rotor?
Is this a flanged model? R indicates reverse flange body. The face to face dimension has not changed, 6-1/2" on both models. FR for flanged reverse model.

I'd imagine there are still 15-55's on suppliers shelves?

TonKa

FWIW, while it is a bit of a bandaid, there are switching relays which will periodically exercise the pump during inactive months. Some modcon boilers have this feature in their settings, too.

ChrisMcc

The impeller is not stuck, it spins freely and there is nothing around the impeller or in the pump housing. Also, on some occasions, I can just rap the motor and it starts. This all makes me think the motor is stuck. I've seen other motors that stopped in a position where they wouldn't restart - I actually have a pond pump that does this occasionally. In that case the shaft is exposed for about 1/2 inch so I can give it a nudge and it starts. The Alphas don't have a way to do this.

Yes, these are FRs - reversed flange. And I haven't found a 15-55 at any of my suppliers. The vertical space is still 6.5" but the problem is that they don't fit horizontally into the same space. If it wasn't an FR then I could rotate the control face 90 degrees but for an FR you can only rotate 180 degrees so it sticks way out the side. I don't have a good way to move the flanges or create more space without some plumbing work.

Thanks,
Chris

ChrisMcc

I'm looking at adding a control to trigger the pumps regularly in the off-season. That seems like a good idea. I need to do a lot of work to not have it actually trigger heat. If I just trigger the thermostat input at the pump controller, it generates a demand signal to my boiler. So I have to work on that.

Jamie Hall

ChrisMcc said:

I'm looking at adding a control to trigger the pumps regularly in the off-season. That seems like a good idea. I need to do a lot of work to not have it actually trigger heat. If I just trigger the thermostat input at the pump controller, it generates a demand signal to my boiler. So I have to work on that.

Do it. This is a very common problem with machinery -- not just those pumps, but almost any rotating machinery which is allowed to just sit. Nothing is really frozen, but the bearings sort of jell and it takes more torque to get them moving again than is available. That's why a smart whack with a spanner often works.

hot_rod

Seems odd, these ECM are DC motors, lots of torque.
What powers them, some of the relay boxes have pump exercise functions in them. The Caleffi ZSR will run pumps for 30 seconds after 72 hours of no heat call.

The new Alphas also have an exercise function.

ScottSecor

One of the reasons we switched to the Alphas (and he 15-58) was due to the same issues your experiencing. Nothing like installing a brand new residential boiler in May and getting called back in October that the pump (or pumps) stopped working. Thankfully we don't get many of these calls anymore (I think I just jinxed myself). We have installed many Alphas, I am not sure if we have had to "free" one yet.

With regard to water quality, I don't think our boiler water is much better than most of the United States. Some systems get treated and some do not, depends on many factors.

HVACNUT

Smaller Grundfos circulators have always done this. The older PSC motor pumps had a screw you could remove at the back if the motor and get access to turn the shaft manually with a screwdriver to free it up.

mattmia2

didn't these used to have a little plug on them so you could stick a screwdriver in them an unstick the rotor after it had been sitting over the summer?

Big Ed_4

Decades back that was an issue , I haven't hit one start of season in years ... Good call , No heat with a hot Grunfos , first tap, tap it with the 7/8" before you spin the blow hole (steam )... Ok Lady all fixed, please sign here

hot_rod

mattmia2 said:

didn't these used to have a little plug on them so you could stick a screwdriver in them an unstick the rotor after it had been sitting over the summer?

I think the electronics hide the access to the back end of the motor

GroundUp

Return the 15-58FR and get a 15-58F. Then there's no issue with fitment

psb75

Just today I had this issue with a "bank" of 9 Grundfoss Alphas. Four of them were showing: - - . I opened them up and the impellers were minimally stuck. Once "free-ed" and put back together they were fine. With one exception--it was hard to hand-turn the impeller and the cartridge seemed terminally "spoiled." I have to admit that two zones are large, radiant floors installed with older black, non-O2 barrier pipe. There's lots of iron oxide in the water. And this was a classic 'seasonal' 5 month "rest" with an October start-up of the heating season. This system has been 13 years in service. Lots of tinkering to do.
These are the original, first version of the Alpha.

ChrisMcc

As I said, I can't use the F, I need the FR, because of the direction of the flanges on all the tightly spaced pumps in this bank so,@GroundUp, that won't work for me.

Yes, the electronics hide the back end of the pump. You can disassemble the pump - which I've done - to spin things and that usually works. My experience and situation are just like @psb75.

I can get Alpha 1s for some reason still but not Alpha 2s. The 1's lack the AutoAdapt but otherwise seem similar. I'm going to try to fit a 15-58FR into a couple of the locations. If they fit they seem like nice(r) pumps and hopefully won't have the same seasonal lockup issue.

psb75

Address the water quality problems and figure out a way to "exercise" (exorcise!) the circulators off-season. Find a hydronics "priest"?

PC7060

Doesn’t seem to have hurt the Alpha 2 sales. Back orders ar pretty common and purchase $ has increased 70% over last 3 years.  

GroundUp

ChrisMcc said:

As I said, I can't use the F, I need the FR, because of the direction of the flanges on all the tightly spaced pumps in this bank so,@GroundUp, that won't work for me.

Yes, the electronics hide the back end of the pump. You can disassemble the pump - which I've done - to spin things and that usually works. My experience and situation are just like @psb75.

I can get Alpha 1s for some reason still but not Alpha 2s. The 1's lack the AutoAdapt but otherwise seem similar. I'm going to try to fit a 15-58FR into a couple of the locations. If they fit they seem like nice(r) pumps and hopefully won't have the same seasonal lockup issue.

Sorry, I had it backwards. I meant: return the 15-58F and get a 15-58FR. Then there's no issue with fitment.

ChrisMcc

@GroundUp, the 58 is a different physical shape so it just doesn't fit in the same size opening with the electronics sticking out the side rather than the bottom. The good news for me is that I was able to fit the 58 into one of the spaces I have, freeing a 55 to go in another space. Crisis averted, for now. It would have been nice though if Grundfos had made the replacement for the discontinued 55 fit in the same space. I can't see a reason why they couldn't. I will say the 58 is a very nice pump. The guided setup via the GO app hung and failed. I suspect it's because when I paired the pump over bluetooth it wanted access to my messages and contacts on my phone. Hard no. So I suspect the app later malfunctioned.

ChrisMcc

@psb75 , not sure this is a water quality issue. When I disassemble these they spin completely freely and there is nothing in the pump section. I just think they come to a rest and don't restart after a while sometimes. I need to OR in a replay that exercises (or exorcises) these when not in use. That's a big wiring project for another day. I think I'll set up a control box with a bunch of Shelly Pro relays and then use that.

hot_rod

ChrisMcc said:

@GroundUp, the 58 is a different physical shape so it just doesn't fit in the same size opening with the electronics sticking out the side rather than the bottom. The good news for me is that I was able to fit the 58 into one of the spaces I have, freeing a 55 to go in another space. Crisis averted, for now. It would have been nice though if Grundfos had made the replacement for the discontinued 55 fit in the same space. I can't see a reason why they couldn't. I will say the 58 is a very nice pump. The guided setup via the GO app hung and failed. I suspect it's because when I paired the pump over bluetooth it wanted access to my messages and contacts on my phone. Hard no. So I suspect the app later malfunctioned.

You can rotate the motor to any of 4 positions in the body if that helps. Remove the 4 allen bolts and rotate it.

HomerJSmith

What about switching it to constant high pressure or high GPM settings to get it going. If possible.

ChrisMcc

@HomerJSmith I did try all those settings to no avail. I hope that the 15-58 proves to be more reliable in this regard, but I do need to start designing my "periodic run" controller for all the pumps to keep them from being idle for months.

ChrisMcc

@GroundUp , you can only rotate the FR versions on 0 and 180 degrees. Which means the electronics stick out one side or the other and that's my issue with the sizing.

Robert_25

ChrisMcc said:

@psb75 , not sure this is a water quality issue. When I disassemble these they spin completely freely and there is nothing in the pump section. I just think they come to a rest and don't restart after a while sometimes. I need to OR in a replay that exercises (or exorcises) these when not in use. That's a big wiring project for another day. I think I'll set up a control box with a bunch of Shelly Pro relays and then use that.

The rotor on ECM circulators can become fouled with iron particles, but you have to disassemble the circulator to see it. If this is the cause of your lockups a magnetic separator should help.

Also - it sounds like you are zoning with circulators. For zones that don't see a lot of run time, the ROI on an ECM circulator is very long. You might be well served to replace failed Alpha's with conventional 15-58 circulators on at least some of the zones.

hot_rod

Disassemble the rotor from the can and see what it looks like
As@robert25 mentioned,ECM circs will attract ferrous particles and slow or jam them

It us wise to have a mag separator in systems with ECM circs

hot_rod

Most all systems with ferrous metals have magnetite. Here are a few Kcoop drained.
Also a pic how water gets into wet rotor circs.
Examples of several ECM circs I disassembled that were "stuck"

Multiple stuck circs need to be disassembled and find the cause. It's not the p[umps fault

ChrisMcc

They always look very clean when disassembled and if I literally just give them a quarter turn (they spin freely) then they will start right back up. I've gotten one of the 15-58s to fit in and it's a nice pump. I hope to prolong things as I don't really want to replace 12 of them

hot_rod

Dud you pull the rotor out if the stainless rotor can? If not you are not into it deep enough

psb75

hot-rod: Thanks, for that last comment. I had not removed the can--and now I understand your pics!

hot_rod

Here is how I disassemble to inspect the insides

Remove motor from rotor can.

carefully wiggle a picket knife and sharpened screwdriver around the flat rubber gasket to pull out the rotor from the stainless can.
 Carefully to not bend the lip or damage the rubber ring

Wipe rotor with paper towel. See how the towel continues to stick to the rotor, indicating magnetite. Also known as “boiler ink” as it looks and stains like ink!

I think this one is 10 years old or more, an original 230 version, it was on an older system I had, cleaned and treated with Rhomar hydronic fluid conditioners.

psb75

Wow. Many thanks hot_rod!

ChrisMcc

@hot_rod, yes, I pulled it all the way out of the can. Appreciate that advice though, it took me the first season a few years ago to realize that was a thing.

psb75

J___H. C____!! I just opened up that Grundfos rotor can, cleaned it with silicone lube spray and now it spins like a top! F.W. Webb supply house was useless in finding me a new rotor cartridge. Now, thanks to hot_rod I know how to fix the damn things--all day long!

psb75

Now, I'm gonna know when a Grundfoss Alpha shows " - -" on its lighted display, it is saying "Open me up, unstick and CLEAN ME"! How many Alphas are out there? Several hundred thousand? This could be a 'career' for someone. Getting heat to people and saving them money!

BenitoMN

TonKa said:

FWIW, while it is a bit of a bandaid, there are switching relays which will periodically exercise the pump during inactive months. Some modcon boilers have this feature in their settings, too.

In my experience this a valid repair. We've had very good experiences with these pumps but when I see the
"--" it's because the circulator is air locked and it typically happens when multiple things come together.

1) The system is zoned with pumps
2) The pumps are mounted vertical with the discharge up
3) The IFCs that come in the pumps are used

Air builds up on the bottom side of the IFC and the impeller becomes "unprimed" and unable to move water

Some fixes:
1) As quoted, use a pump relay that exercises the pumps every 72 hours during the off season, this prevents too much air from building up in the pump

2) Remove the IFCs from the pumps and install spring check valves about 12"-18" way from the pump outlet, this gives a reservoir for air to accumulate outside of the pump so it doesn't become unprimed

hot_rod

I know the pump manufacturers have our best interest at heart with IFCs.
However, they are too close to the discharge. They can trap air as @BenitoMN mentioned, and they are in fairly turbulent conditions. I suspect that is why some are short lived, they rattle their brains out.

12” or more downstream of a circulator, depending on pipe diameter, is where they would be better located.

Always a hydronic specific check. No place for swing checks in hydronics other than power outage, overheat valves on fossil fueled boilers

PC7060

Moved check valve question new discussion. 

https://forum.heatinghelp.com/discussion/193972/replacement-check-valve/p1?new=1

ChrisMcc

@BenitoMN - the configuration you describe as problematic is exactly mine. I need to build out something this year to make sure the pumps get exercised in the off season.